Repairing laser welding method and repairing laser welding device

Abstract

Irradiation with a laser beam is performed along a welding bead, while the laser beam is aimed, as an irradiation point of the laser beam, at a contact point between a deck plate and a U-rib that is contained in a non-welded portion of a root part, from a side of the welding bead of the root part. Thereby, it is possible to remove a crack beginning at the non-welded portion of the root part generated at a joining portion between the deck plate and the U-rib of a steel floor slab, by the irradiation with the laser beam.

The invention claimed is: 
     
         1 . A repairing laser welding device that melts and eliminates a crack by irradiation with a laser beam, the crack being generated beginning at a non-welded portion of a root part between a first welded material and a second welded material obliquely joined to a surface of the first welded material by fillet welding, the repairing laser welding device comprising:
 a laser oscillator;   a laser head that performs irradiation with the laser beam supplied from the laser oscillator;   a head drive mechanism that moves the laser head along a welding bead at the root part; and   a tracing mechanism that causes an irradiation point of the laser beam to trace a contact point between the first welded material and the second welded material, the laser beam being emitted from the laser head that is moved along the welding bead by the head drive mechanism, the contact point being contained in the non-welded portion of the root part, the tracing mechanism comprising:   two tracing legs disposed at the laser head, each including a roller at their respective distal end and pressed against a downward-facing surface of the first welded material and a side edge of the second welded material, respectively.   
     
     
         2 . The repairing laser welding device according to  claim 1 , further comprising a weaving mechanism that performs weaving with the laser beam in a direction crossing the welding bead. 
     
     
         3 . The repairing laser welding device according to  claim 2 , wherein the irradiation point of the laser beam is set such that at least an outer edge of a spot of the laser beam contacts with the contact point between the first welded material and the second welded material, the contact point being contained in the non-welded portion of the root part. 
     
     
         4 . The repairing laser welding device according to  claim 1 , wherein the irradiation point of the laser beam is set such that at least an outer edge of a spot of the laser beam contacts with the contact point between the first welded material and the second welded material, the contact point being contained in the non-welded portion of the root part. 
     
     
         5 . A repairing laser welding method for melting and eliminating a crack by irradiation with a laser beam using the repairing laser welding device according to  claim 1 , the crack being generated beginning at a non-welded portion of a root part between a first welded material and a second welded material obliquely joined to a surface of the first welded material by fillet welding, wherein
 the irradiation with the laser beam is performed along a welding bead at the root part while the laser beam is aimed at a contact point between the first welded material and the second welded material as an irradiation point of the laser beam, from a side of the welding bead, the contact point being contained in the non-welded portion of the root part.   
     
     
         6 . The repairing laser welding method according to  claim 5 , wherein the laser beam is caused to pass along the welding bead multiple times while the irradiation point of the laser beam is shifted from the contact point to the side of the welding bead. 
     
     
         7 . The repairing laser welding method according to  claim 6 , wherein the irradiation with the laser beam is performed along the welding bead while weaving with the laser beam is performed in a direction crossing the welding bead. 
     
     
         8 . The repairing laser welding method according to  claim 7 , wherein when the laser beam is aimed at the contact point between the first welded material and the second welded material as the irradiation point of the laser beam, the contact point being contained in the non-welded portion of the root part, the irradiation point is set such that at least an outer edge of a spot of the laser beam contacts with the contact point. 
     
     
         9 . The repairing laser welding method according to  claim 8 , wherein the irradiation with the laser beam is performed while a welding material is supplied. 
     
     
         10 . The repairing laser welding method according to  claim 7 , wherein the irradiation with the laser beam is performed while a welding material is supplied. 
     
     
         11 . The repairing laser welding method according to  claim 6 , wherein when the laser beam is aimed at the contact point between the first welded material and the second welded material as the irradiation point of the laser beam, the contact point being contained in the non-welded portion of the root part, the irradiation point is set such that at least an outer edge of a spot of the laser beam contacts with the contact point. 
     
     
         12 . The repairing laser welding method according to  claim 11 , wherein the irradiation with the laser beam is performed while a welding material is supplied. 
     
     
         13 . The repairing laser welding method according to  claim 6 , wherein the irradiation with the laser beam is performed while a welding material is supplied. 
     
     
         14 . The repairing laser welding method according to  claim 5 , wherein the irradiation with the laser beam is performed along the welding bead while weaving with the laser beam is performed in a direction crossing the welding bead. 
     
     
         15 . The repairing laser welding method according to  claim 14 , wherein when the laser beam is aimed at the contact point between the first welded material and the second welded material as the irradiation point of the laser beam, the contact point being contained in the non-welded portion of the root part, the irradiation point is set such that at least an outer edge of a spot of the laser beam contacts with the contact point. 
     
     
         16 . The repairing laser welding method according to  claim 15 , wherein the irradiation with the laser beam is performed while a welding material is supplied. 
     
     
         17 . The repairing laser welding method according to  claim 14 , wherein the irradiation with the laser beam is performed while a welding material is supplied. 
     
     
         18 . The repairing laser welding method according to  claim 5 , wherein when the laser beam is aimed at the contact point between the first welded material and the second welded material as the irradiation point of the laser beam, the contact point being contained in the non-welded portion of the root part, the irradiation point is set such that at least an outer edge of a spot of the laser beam contacts with the contact point. 
     
     
         19 . The repairing laser welding method according to  claim 18 , wherein the irradiation with the laser beam is performed while a welding material is supplied. 
     
     
         20 . The repairing laser welding method according to  claim 5 , wherein the irradiation with the laser beam is performed while a welding material is supplied.